Wednesday, December 15, 2010

Removing the BSA A10 swing arm and silent block bushings.

Currently I have two A10 frames in my shop. One is mine for my future TriBSA and the other is my neighbor Woody's. who is restoring his. My frame is the later type which has the hollow swing arm spindle for a right hand side rear brake. Woody's is a 1955 and it is still seized up inside those silent block bastards.

Anyway, I applied some parts blaster around the nut on the right hand side of the frame to help loosen everything up. I removed the nut as well as the small bolt on the left side that holds the flat side of the main spindle-bolt to the frame. I rethreaded the nut to the spindle (just a couple of threads so that there was an inch of thread exposed below it), propped the bikes left side up off the floor with a 2x4 and with a piece of scrap wood as a buffer, I gave it a few sharp taps with a mallet. Eureka! It eased down an inch. I removed the nut and using a spare socket (I believe 14mm was a close match) I tapped the spindle though the swing arm, adding spare 14mm sockets as the spindle sunk deeper and deeper until it popped out the other side. Now the 1st thread on the spindle was a bit bodged up, but I took it to the grinder to bevel it out and the nut went right back on.

The bushings are two metal sleeves, one inner and one outer, separated by a rubber layer. Using a torch (outside of course) I burned the tip of the swing arm where the rubber was exposed. The rubber soon caught fire and with the continuous flame of the torch the rubber bubbled up and burned out in a few minutes - all from the tip of the swing arm - as the rubber burned off the rubber deeper inside expanded and bubbled out. after a few minutes I pulled the inner metal portion of the bushing out with some vice grips. I repeated this to the second side. With both inner sleeves removed I torched through the swing arm tube and burned out the rest of the rubber and scraped it out with metal rod. I kept waiting for the fire company or the EPA to show up as flakes of burning rubber embers were swirling around the ally and toxic fumes from the burning rubber surely offended at least a few neighbors.

The outer sleeves of the silent block bushings are the real bitch. They are two, roughly 2-3 inch long tubes pressed into the swing arm very tightly. I tried using a Dremmel with a cutting tool to score a line across the metal sleeve. The bit wore out before I got too far. I ended up spending the next hour and a half swearing sweating and breaking tools (2 files a hack saw blade and two screwdrivers, but I finally got a couple of cuts into the inner sleeve where I could pry it out with some channel locks. Not a pretty job and there's still one more inner sleeve to go.

Burning just the tips allowed the rubber to bubble up.

With vice grips I pulled the flaming inner sleeve out with ease.

The inner sleeve.

Burning out the excess rubber. I then scraped out the rest.

Voila!

Pulling the mangled outer sleeve from the swing arm.

I really had to butcher the sleeve to get it out.

Next up is Woody's older model with the solid bolt-spindle. This one is really seized.